Method and apparatus for controlling well pressure in open-ended casing

ABSTRACT

A system and method for preventing blowouts during the deployment of a casing string into a wellbore. The system includes securing a casing coupling to a casing string and securing a retrievable check valve within the casing coupling. The retrievable check valve allows fluid from the surface to be pumped through the retrievable check valve. However, the retrievable check valve prevents upward fluid flow from the wellbore through the retrievable check valve to the surface.

FIELD OF THE INVENTION

[0001] The present invention relates generally to a method and apparatusto prevent a well blowout during the installation of a casing stringinto a wellbore, and particularly to a retrievable check valve systemutilized to prevent such a blowout.

BACKGROUND OF THE INVENTION

[0002] A typical production well consists of a wellbore lined with awellbore casing. The casing is comprised of a string of tubular steelcasing joints assembled together. As the casing string is lowered intothe wellbore. Additional casing joints are added to the casing stringuntil the wellbore is fully lined.

[0003] An imbalance of pressures in the wellbore may cause a blowout asthe casing string is lowered into the wellbore. The pressure imbalancemay result from a low pressure/high permeability formation in the openwellbore that causes gas to migrate to a column of fluid in thewellbore. If a blowout results, fluid flows toward the surface throughthe inside of the casing string.

[0004] A blowout may be prevented by placing a casing shoe check valveat the bottom of the casing string. However, the casing shoe check valvecannot be used in some applications, such as where the casing string isnot hydraulically sealed above the valve. Another method utilizes apacker placed at the bottom, or close to the bottom, of the casingstring. The packer includes a check valve and may support a stab-incementing sleeve. However, this device permanently restricts access tothe lower section of the casing and cannot be used where access isneeded to place a tool near the bottom of the casing. Additionally, awellbore may have several branches extending from a central verticalwellbore. In this event, a multi-branch junction is lowered into thewellbore to merge the branches into a single column. However, the casingshoe check valve and packer described above are unsuitable for use witha multi-branch junction.

[0005] If the conditions are suitable, the casing string may be loweredinto the wellbore without any mechanism to prevent a blowout. However,even in this situation, some localities do not permit a casing string tobe lowered into a wellbore without a mechanism in place to prevent ablowout.

[0006] It would be advantageous to have a flow control device readilyuseable with a casing string, especially a casing string having amulti-branch junction. Additionally, it would be advantageous to have aflow control device that could be retrieved quickly, easily, andcompletely once the casing string is disposed in the wellbore.

SUMMARY OF THE INVENTION

[0007] The present invention features a system for deploying casing intoa wellbore. The system comprises a casing string and a deployment systemfor lowering the casing string into a wellbore. The system alsocomprises a check valve assembly that is securable to the casing string.The check valve assembly prevents blowouts by preventing fluid fromflowing upward through the casing string. Also, the system is operableto release the check valve assembly from the casing string and totransport the check valve assembly to the surface location.

[0008] According to another aspect of the present invention, a system isfeatured for controlling well pressure in a wellbore during theinsertion of a casing string. The system comprises a check valveassembly securable to the casing. One portion of the check valveassembly is a housing. A check valve is disposed within the housing toallow fluid to flow through the check valve assembly from a surfacelocation. A sealing member is deployed to form a seal between thehousing and the casing. Additionally, the check valve assembly has asecuring member that is configured for engagement with the casing. Thecheck valve assembly also has a releasing member that is operable torelease the securing member from the casing.

[0009] According to another aspect of the present invention, a method ofdeploying casing into a wellbore is featured. The method comprisessecuring a blowout prevention assembly to a casing string. Additionally,the method comprises deploying the casing string in a wellbore. Themethod also comprises retrieving the blowout prevention assembly fromthe casing string after the casing string is deployed.

[0010] The above description of various aspects of the present inventionis merely exemplary and is not intended to limit the scope of theinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The invention will hereafter be described with reference to theaccompanying drawings, wherein like reference numerals denote likeelements, and:

[0012]FIG. 1 is a front elevational view of a system for deployingcasing and a blowout prevention device into a wellbore, according to apreferred embodiment of the present invention;

[0013]FIG. 2A is a front elevational view of a top portion of aretrievable check valve deployed near the bottom of a casing string,according to a preferred embodiment of the present invention;

[0014]FIG. 2B is a front elevational view of a bottom portion of aretrievable check valve deployed near the bottom of a casing string,according to a preferred embodiment of the present invention;

[0015]FIG. 3 is an alternate embodiment of a check valve assembly fordeployment with a casing to prevent a blowout;

[0016]FIG. 3A is a cross-sectional view taken along line 3A-3A of FIG.3; and

[0017]FIG. 4 is a front elevational view of a system for deploying amulti-branch junction at the end of a casing string having a retrievablecheck valve to prevent a blowout.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Referring generally to FIG. 1, a system 20 for deploying a casingstring 22 into a wellbore 24 is featured. A rig system 26 is used toassemble casing joints 28 into casing string 22. Casing string 22 islowered further into wellbore 24 as each new casing joint 28 is added tothe casing string 22. Casing joints 28 are tubular and have a hollowinterior 29. A retrievable check valve 30 is secured to a casingcoupling 32 near the bottom of casing string 22. Casing coupling 32 maybe a modified casing joint or a coupling joint used to connect twocasing joints 28.

[0019] Retrievable check valve 30 is configured so that fluid may bepumped through hollow interior 29 and retrievable check valve 30. Thisallows fluid to be pumped down into casing string 22 to clean theinterior of casing string 22, to compensate for fluid losses, to changethe nature of the column of fluid in the casing string 22 and wellbore24, etc. However, retrievable check valve 30 prevents fluid in wellbore24 from flowing upward through the casing string 22. Thus, if there isan unbalanced pressure or a gas migration into the column of fluid,retrievable check valve 30 prevents well fluid from circulating to thesurface inside the hollow interior 29 of casing string 22. Additionally,retrievable check valve 30 is configured such that it is secured tocasing coupling 32 during the lowering of casing string 22 into wellbore24. However, valve 30 is retrievable from casing string 22 once casingstring 22 has reached its desired position in wellbore 24.

[0020] In the illustrated embodiment, retrievable check valve 30 hassecuring members 34 which engage a landing 36, or landings, on theinside surface of casing coupling 32 to secure retrievable check valve30 to casing coupling 32. Landing 36 and securing members 34 may beconfigured in a variety of different configurations. Preferably, landing36 is a recess in the interior surface of casing coupling 32 andsecuring members 34 are a plurality of keys configured for engagementwith the recess.

[0021] Retrievable check valve 30 has a sealing member 38 that preventsfluid in wellbore 24, below retrieval check valve 30, from flowingbetween retrievable check valve 30 and casing string 22 towards thesurface 40. However, an internal fluid path 42 and a check valve 44allow fluid to be pumped from surface 40 through retrievable check valve30 into a lower portion 46 of wellbore 24.

[0022] A retrieving member 48 is used to remove retrievable check valve30 from casing string 22. A retrieval tool 50 is lowered onto retreivingmember 48 from the surface. Retrieval tool 50 may be deployed in avariety of ways, such as by a wireline, production tubing, or coiltubing. In the illustrated embodiment, retrieval tool 50 is deployed bya wireline 52. If the well inclination creates difficulty in latchingretrieval tool 50 onto retrieving member 48, a liquid may be used topump down retrieval tool 50 towards retrievable check valve 30, as knownto those of ordinary skill in the art.

[0023] To disengage retrievable check valve 30 from casing coupling 32 apulling force is applied by, for example, wireline 52 to retrieval tool50 and retrieving member 48. The pulling force applied to retrievingmember 48 causes securing member 38 to retract from landing 36, freeingretrievable check valve 30 from casing coupling 32. Wireline 52 may thenbe used to raise retrievable check valve 30 to the surface 40. Casingstring 22 provides full bore flow through hollow interior 29 oncereceivable check valve 30 is removed, because landing 36 is recessedinto casing coupling 32. A bumper sub may be used to assist theretrieval tool 50 in raising retrievable check valve 30 to the surface.

[0024] Referring generally to FIGS. 2A and 2B, an exemplary embodimentof a retrievable check valve 30 is featured. Retrievable check valve 30has a central mandrel 58 that extends through an upper portion 60 ofretrievable check valve 30. Retrieving member 48 is coupled to, orformed from a portion of mandrel 58. In the illustrated embodiment,mandrel 58 is biased downward by a spring 62. A plurality of securingmembers 34 are held in landings 36 by engagement members 66. Engagementmembers 66 are held in position by mandrel 58.

[0025] Retrieval tool 50 has a snap-on latching assembly 68 that latcheson to retrieving member 48. Retrieving member 48 and snap-on latchingassembly 68 are configured for mating engagement with each other. Apulling force applied to retrieving member 48 by retrievable tool 50will displace mandrel 58 from its initial position relative to upperportion 60. In the displaced position of mandrel 58, the engagementmembers 66 are no longer held in position by mandrel 58. One or morespring members 70 bias the securing members 34 toward a central axis 71.Spring members 70 operate to retract each securing member 34 from eachlanding 36 when engagement members 66 are no longer held in position bymandrel 58. Retrievable check valve 30 is then free to be transported tosurface 40 by retrieval tool 50.

[0026] Alternatively, retrievable check valve 30 may be configured suchthat each securing member 34 is biased into a secured position againsteach corresponding landing 36. Thus, retrieving member 48 may beoperated to overcome the bias to disengage securing member 34 fromlanding 36.

[0027] Retrievable check valve 30 also has a sealing member 72. Sealingmember 72 is disposed between mandrel 58 and upper portion 60 to preventwellbore fluid from entering and damaging the internal components ofretrievable check valve 30.

[0028] Referring generally to FIG. 2B, the lower portion of retrievablecheck valve 30 is featured. A seal assembly, such as a multi-cup sealassembly 74 is used to form a seal between the retrievable check valve30 and the interior surface 75 of the casing string 22. Multi-cup sealassembly 74 comprises a series of rubber discs oriented to naturallyoppose the upward flow of fluid. Multi-cup seal assembly 74 is securedto a core section 76 of retrievable check valve 30. Core section 76 issecured to upper portion 60 and a lower portion 78 of retrievable checkvalve 30 by, for example, threaded engagement. Lower portion 78 is, inturn, coupled to a base portion 80 disposed generally opposite coresection 76 as illustrated.

[0029] Fluid path 42 provides a path for fluid to bypass multi-cup sealassembly 74.

[0030] Flow path 42 extends through upper portion 60, core section 76,lower portion 78, and bottom portion 80. Check valve 44 is disposed inbottom portion 80. Check valve 44 allows fluid to flow from the surface40 through flow path 42 to the lower portion 46 of wellbore 24.Additionally, check valve 44 prevents fluid from flowing from the lowerportion 46 of wellbore 24 through flow path 42 to the surface 40, thuspreventing a blowout.

[0031] Check valve 44 may be configured in a variety of ways, such aswith a ball or flapper valve. In the illustrated embodiment, check valve44 comprises a valve disc 82 biased against a valve seat 84 by a spring86. Check valve 44 includes a hole 88 for static pressure equalizationacross valve disc 82 to prevent the valve from opening inadvertently dueto a pressure differential across valve disc 82.

[0032] When fluid is pumped down into casing string 22, the fluid can besufficiently pressurized to overcome the force of spring 86 and tounseat valve disc 82 from valve seat 84. This provides a flow path forfluid from surface 40 into wellbore 24. Contrariwise, fluid pressure inlower portion 46 of wellbore 24 acts to further seat valve disc 82against valve seat 84, unless overcome by fluid pressure applied abovevalve 44.

[0033] Referring generally to FIGS. 3 and 3A, an alternate embodiment ofa retrievable check valve 90 is featured. In this embodiment,retrievable check valve 90 comprises a mandrel 92 disposed within a body94. O-rings 95 are used to form a seal between mandrel 92 and body 94.Fluid pumped from surface 40 is directed through a flow channel 96 thatextends through mandrel 92 and body 94. A swab cup 98 is used to form aseal between retrievable check valve 90 and casing string 22. In theillustrated embodiment, retrievable check valve 90 is secured to casingstring 22 by key plungers 100, e.g., three key plungers. The three keyplungers 100 are seated into three corresponding landing profiles 36 oncasing coupling 32.

[0034] A check valve assembly 102 is disposed within a central cavity104 of retrievable check valve 90 to prevent fluid from flowing throughflow channel 96 to surface 40. Check valve 102 has a number ofcomponents assembled within a structural member 106. Side seals 108 aredisposed on the exterior of structural member 106 to form a seal betweencheck valve 102 and the inner surface defining cavity 104. Check valve102 includes a valve disc 110 and a valve seal 112. Valve 110 and valveseal 112 are biased against a surface 114 by a spring 116. A valve guide118 is used to direct a movement of valve 110 and valve seal 112. Spring116 is secured to valve 110 by a valve seal disk 120.

[0035] A retrieval tool 50 may be lowered or pumped down to secure tool50 to a nipple profile 124 extending circumferentially around theinterior surface 125 of mandrel 122. A pulling force is applied tomandrel 92 to draw mandrel 92 upward to release the three key plungers100 from landing profile 36. During upward movement, the three keyplungers 100 are biased towards the central axis 126 of retrievablecheck valve 90. In the secured position, the three key plungers are heldin place by mandrel 92. Mandrel 92 is configured with an angled portion128. Angled portion 128 allows the biasing element to retract the threekey plungers 100 towards axis 126 and out of landing profile 36,releasing retrievable check valve 90 from the casing string 22.Retrieval tool 50 is then used to raise check valve assembly 102 to thesurface.

[0036] Referring generally to FIG. 4, a system is featured forpreventing a well blowout as a casing string 22 and a multi-branchjunction 130 are lowered into a wellbore. The multi-branch junction 130is secured to the lower end of casing string 22. A retrievable checkvalve 30 is secured within casing string 22 in proximity to themulti-branch junction 130. In the illustrated embodiment, multi-branchjunction 130 merges fluid flow from two fluid flow paths 132. However,multi-branch junction 130 may be used to merge more than two fluid flowpaths. Retrievable check valve 30 prevents wellbore fluid 134 fromentering casing string 22 through multi-branch junction 130 and flowingup through the hollow interior 29 of casing string 22 to the surface.

[0037] It will be understood that the foregoing description is ofpreferred embodiments of this invention, and that the invention is notlimited to the specific forms shown. For example, a variety ofmechanisms may be used to retrieve the retrievable check valve, such asa wireline, production tubing, or coil tubing. Additionally, the sealingmember may be above or below the securing member in the wellbore.Furthermore, fluid may flow through a single fluid channel in theretrievable check valve or multiple fluid channels. These and othermodifications may be made in the design and arrangement of the elementswithout departing from the scope of the invention as expressed in theappended claims. Also, it is the intention of the applicant not toinvolve 35 U.S.C. §112, paragraph 6 for limitations of any of the claimsherein, except for those in which the claim expressly uses the words“means for” together with an associated function.

What is claimed is:
 1. A system for deploying casing into a wellbore,comprising: a casing string; a deployment system for lowering the casingstring into a wellbore from a surface location; and a check valveassembly securable to the casing string, the check valve assemblypreventing fluid from flowing upward through the casing string whereinthe check valve assembly may selectively be released from the casingstring to transport the check valve assembly to the surface location. 2.The system as recited in claim 1, wherein the check valve assemblyallows fluid to flow downwardly through the check valve assembly fromthe surface location.
 3. The system as recited in claim 1, furthercomprising a multi-branch junction secured to the casing string.
 4. Thesystem as recited in claim 1, comprising: a retrieval device, theretrieval device being operable to retrieve the retrievable check valvefrom the casing string.
 5. The system as recited in claim 1, wherein thecasing string comprises a casing coupling configured for engagement withthe check valve assembly.
 6. The system as recited in claim 1, whereinthe check valve assembly comprises: a housing; a check valve disposedwithin the housing; and a sealing member configured to form a sealbetween the housing and an interior surface of the casing string orcasing coupling.
 7. The system as recited in claim 4, wherein theretrieval device is deployed by a wireline.
 8. The system as recited inclaim 4, wherein the retrieval device is deployed by tubing.
 9. Thesystem as recited in claim 5, wherein the casing coupling is configuredwith a recess in an interior surface and the check valve assemblycomprises a securing member configured for engagement with the recess.10. The system as recited in claim 9, further comprising: a securingmechanism to maintain the, the securing mechanism being operable by theretrieval tool to disengage the securing member from the casing string.11. The system as recited in claim 10, wherein the securing mechanism isoperated by the retrieval tool to disengage the securing member from thecasing string.
 12. A system for controlling well pressure in a wellboreduring the insertion of a casing, comprising: a check valve assemblysecurable to the casing, comprising: a housing; a check valve disposedwithin the housing and oriented to allow fluid flow through the checkvalve assembly from a surface location; a sealing member configured toform a seal between the housing and the casing; a securing memberconfigured for engagement with the casing; and a releasing member, thereleasing member being operable to release the securing member from thecasing.
 13. The system as recited in claim 12, further comprising: areleasing device, the releasing device being operable to operate thereleasing member to release the securing member from the casing.
 14. Thesystem as recited in claim 12, further comprising a multi-branchjunction secured to an end of the casing string.
 15. The system asrecited in claim 12, wherein the check valve forms a barrier to fluidflow though the casing from the wellbore to the surface.
 16. The systemas recited in claim 13, wherein the releasing device is deployed by awireline. 17 The system as recited in claim 13, wherein the releasingdevice is deployed by tubing.
 18. A method of deploying casing into awellbore, comprising: securing a blowout prevention assembly to a casingstring; deploying the casing string in a wellbore; and retrieving theblowout prevention assembly from the casing string after the casingstring is deployed.
 19. The system as recited in claim 18, whereinsecuring comprises configuring the casing string with a casing coupling.20. The method as recited in claim 18, further comprising: disposing amulti-branch junction at the lower end of the casing string.
 21. Themethod as recited in claim 18, wherein securing comprises configuringthe blowout prevention assembly with a check valve oriented to enablefluid to be pumped downward from the surface through the casing stringand the blowout prevention assembly.
 22. The method as recited in claim18, wherein lowering comprises using a rig system to assemble the casingstring.
 23. The method as recited in claim 18, wherein retrievingcomprises deploying a retrieval tool to release the blowout preventionassembly from the casing coupling.
 24. The method as recited in claim21, further comprising: pumping fluid from the surface through theblowout prevention assembly.
 25. The method as recited in claim 21,wherein configuring comprises disposing a coupling member in the casingstring configured for mating engagement with the blowout preventionassembly.
 26. The method as recited in claim 25, wherein retrievingcomprises providing a pulling force to the blowout prevention assemblyto disengage the retrieval tool from the coupling member.
 27. Aretrievable valve, comprising: a body, the body being securable towellbore casing; a latch coupled to the body, the latch being operableto release the body from the wellbore casing; and a check valve, thecheck valve enabling fluid flow through the body.
 28. The retrievablevalve as recited in claim 27, wherein the retrievable valve isconfigured to enable fluid to flow downwardly through the check valvefrom a surface location.
 29. The retrievable valve as recited in claim27, further comprising a multi-branch junction secured to the casingstring.
 30. The retrievable valve as recited in claim 27, comprising: aretrieval device, the retrieval device being operable to operate thelatch to release the retrievable valve from the casing string.
 31. Theretrievable valve as recited in claim 27, wherein the wellbore casingcomprises a casing coupling configured for engagement with theretrievable valve.
 32. A well completion string, comprising: a casingstring having a multilateral junction, the multilateral junctioncomprising a junction of at least two flow branches; and a check valvedisposed in the casing string above the multilateral junction.
 33. Thewell completion string as recited in claim 32, wherein the check valveis retrievable.
 34. The well completion string as recited in claim 32,wherein the check valve comprises a latch, the latch being operable torelease the check valve from the casing string.
 35. The well completionsystem as recited in claim 34, wherein the latch is operable by aretrieval tool extending from the surface.
 36. The retrievable valve asrecited in claim 32, wherein the well completion string is configured toenable fluid to flow downwardly through the check valve and multibranchjunction from a surface location.
 37. A well completion system,comprising: a profile in a casing string; and a casing shoe having alatch, the latch being adapted to cooperatively and selectively maintainthe casing shoe in the casing.
 38. The system as recited in claim 37,wherein the casing shoe comprises: a body, the body being securable towellbore casing; and a check valve, the check valve enabling fluid flowthrough the body.
 39. The as recited in claim 37, wherein the checkvalve is oriented to enable fluid to flow downwardly through the checkvalve from a surface location.
 40. The system as recited in claim 37,wherein the latch is operated from a remote location.